The forms and severity of cardiac complications were investigated in patients with asymptomatic thalassemia intermedia and thalassemia major by M-mode, bi-dimensional echocardiography (ECHO) and echo-Doppler. Twenty-eight patients of both sexes with beta-thalassemia intermedia (beta-TI), mean age 23.2 +/- 6.3 years, untransfused or minimally transfused, were compared to 42 age- and sex-matched subjects with thalassemia major, who were regularly treated with hemotransfusive therapy [pre-transfusion hemoglobin (Hb) values 9.5 +/- 0.9 g/dL] and iron chelation. All patients were splenectomized. Age and sex matched healthy control subjects were randomly selected. beta-Thalassemia major (beta-TM) patients showed a marked reduction in contractile state and a milder left ventricular (LV) enlargement than beta-TI patients. Cardiac output (CO) and cardiac index (CI) were increased in both groups of patients but appeared significantly higher in beta-TI patients with consequent altered LV diastolic function indices. In addition, beta-TI patients had reduced indices of pulmonary artery flow related to long-term chronic anemia rather than iron overload. The progressive rise in CO and CI casts doubts on the current management of beta-TI syndromes.